--检查在线用户的重复ip
select ip from web_session group by ip having count(*)>1;

--检查订单表是否有错误的重复记录
select a.id,b.username,a.no,a.color,a.bx from web_order a,web_client b where a.uid=b.id group by a.uid,a.iid,a.color,a.bx having count(*)>1

--新增一个用户
grant all privileges on *.* to hehe@localhost identified by "hehe" WITH GRANT OPTION;

--授权远程连接
grant all privileges on *.* to hehe@'%' identified by "hehe";

--修改表的字段
alter table web_zk modify zk decimal(5,2) unsigned not null default '0.00';

--创建索引
create index ind_upath on web_order (upath);  

--输出查询结果到文本文件
select * from web_order into outfile 'c:/1.txt';

--备份数据库
mysqldump -hlocalhost -uhehe --default-character-set=latin1 -p edt > d:\edt.sql

--恢复数据库
mysql -hlocalhost -uhehe -p edt_ybd < D:\web\edt\cli\hz\ibd\mysql_ibd_2018x_20171107185606.sql


--慢查询日志
show variables like '%quer%';        slow_query_log的值为ON为开启慢查询日志，OFF则为关闭慢查询日志。
                                     long_query_time 指定了慢查询的阈值，即如果执行语句的时间超过该阈值则为慢查询语句，默认值为10秒。
set global slow_query_log=on;        开启慢查询日志
show global status like '%slow%';    显示慢查询状态